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As if APC batteries weren’t bad enough already

Upon hauling home a failed APC Back-UPS RS 1500VA (BR1500I) and cracking it open in the shop, I was greeted by a new sort of battery failure:

The battery casing has a very large crack in it.

Yes, the plastic casing on one of the batteries has cracked – and it isn’t even just a minor crack; about 80% of the end wall of the cell can be bent up with a screwdriver.

Amazingly, the cell is still working. The battery was charged at a decent 12,6V when I measured it. The ESR of the cell, however, is not as healthy. It would barely power the UPS when idle.

This is how it looked when I pulled the battery pack out.

The crack reaches around all the way. The plastic is only attached at the top.

I very much doubt that this has anything to do with the UPS itself, it seems far more likely to be a manufacturing defect on the battery. The UPS charges the batteries normally, and the other battery in the pack shows no signs of abnormal wear, not even swelling.

I think this is a quite serious issue indeed. If a consumer was to remove the battery pack, oblivious to the potentially corrosive contents of the battery cells, someone could get seriously hurt.

2 thoughts on “As if APC batteries weren’t bad enough already”

Rather than a problem with the batteries themselves, it’s a problem with the charging voltage.
In most APC ups systems, the charging voltage is set too high, leading to heat development and battery expansion, and early battery deaths.

That is correct – and I adjust the charging voltage on all my UPSes. However, this battery showed no signs of over-heating; the cracked cell wasn’t even swollen. The plastic “tab”, when pressed back, would sit flush along the rest of the battery wall.